1. Field of the Invention
This invention relates generally to termination structures for semiconductor devices, and more specifically, to trench type terminations for silicon carbide semiconductor devices.
2. Description of the Prior Art
Silicon carbide (SiC) is becoming a mature technology for high power devices. For example, trench technologies are being applied to SiC to fabricate advanced trench type devices, such as JFET transistors and JBS rectifiers. With these advancements edge terminations for SiC power devices are a subject of significant interest for improving the blocking capability efficiency.
Many studies and patents have shown the use of field plate, guard ring, and JTE planar type terminations. However, in trench type devices, the epitaxially silicon depletion starts at the trench bottom, thereby making these planar type terminations inefficient. In addition, while the guard ring technique is well known in silicon technology, it has not been widely used in SiC technology due primarily to the difficulty in optimizing the ring spacing in SiC technology. For example, literature has reported achieving only about 50% of the ideal breakdown voltage using the guard ring technique. While the JTE technique is known to provide good termination efficiencies, this technique requires fabrication processes that are significantly more complex than that used for the guard ring and field termination techniques.